Microplastics

However, we also describe plastics according to their basic chemical structure as polyethylene (PE), polypropylene (PP), polyamide (PA), polyvinyl chloride (PVC), polystyrene (PS), polyurethane (PU) and polyethylene terephthalate (PET) [10,13]. These are the structures extensively found in the majority of research.

Photographs of microplastics from fish

FIGURE 12.2 Photographs of microplastics from fish.

Flow-diagram of types of plastics information collected

FIGURE 12.3 Flow-diagram of types of plastics information collected (Adapted from Anderson PJ et al. Environ Pollut 2017,225,223-231; Lee KW et al. Environ Sci Technol 2013, 47(19), 11278-11283; Hidalgo-Ruz V. and Thiel M. In M. Bergmann, L. Gutow, M. Klages (eds.), Marine Anthropogenic Litter, Heidelberg, New York, Dordrecht, London: Springer Cham, 2015, pp. 429-447.)

Methods of Ingestion of MPs by Fishes

Ingestion is one of the most common factors associated with plastic debris, having been reported in more than 270 taxa [24] from a variety of trophic levels [18]. One of the most affected taxa is fish. Plastic and other debris may be intentionally ingested by fish [18,24]. Incidental ingestion happens with the ingestion of natural food items [25], or through trophic transfer, when the fish consumes prey that has already ingested plastic debris [26,27]. On the other hand, intentional ingestion occurs when the plastic material is mistaken for food, especially bottom algae and fragment-like foods [28]. Evidence suggests that intentional ingestion of plastic is most common in fish. For instance, marks left in large plastic debris suggest fish frequently attack and bite plastic items present in the environment [29], and laboratory experiments suggest fish larvae feed preferentially on plastic particles when exposed to both microplastics and natural food [30]. The ingested MPs usually get accumulated inside the stomach, gut and intestinal lining of the fishes, which we examine to observe whether or not the ingestion has happened (Table 12.1; Figure 12.4).

Data Analysis

Plastic debris ingestion in fish from different freshwater habitats like rivers, estuaries and lakes from different locations across the globe was examined by different researchers, and

TABLE 12.1 Plastic Debris Ingestion in Fish from Freshwater Habitats (Rivers, Estuaries and Lakes)

Environment

Location

Species

Frequency %

Reference

Lake

Lake Victoria (Africa)

bates niloticus

20

[31]

Lake

Lake Victoria (Africa)

Oreochromis niloticus

20

[31]

Estuary

Goina Estuary (Brazil)

Cathorops spixi

18

[32]

Estuary

Goina Estuary (Brazil)

Cathorops agassizzi

33

[32]

Estuary

Goina Estuary (Brazil)

Sciades berzbergii

18

[32]

Estuary

Goina Estuary (Brazil)

Stellifer brasiliensis

6.9

[33]

Estuary

Goina Estuary (Brazil)

Stellifer stellifer

9.2

[33]

Estuary

Goina Estuary (Brazil)

Eugeress brasilianus

16.3

[34]

Estuary

Goina Estuary (Brazil)

Eucinostomos

9.2

[34]

melanopterus

Estuary

Goina Estuary (Brazil)

Diapterus rbombeus

11.4

[34]

River

Brazos River Basin (US)

Leportis megalotis

44

[25]

River

Brazos River Basin (US)

Lepomis macrocbirus

45

[25]

River

7 Rivers (France)

Gobio gobio

9.5 4 ?

[35]

River/

lake

Various (USA)

26 species

5-29

[36]

River

Pajeu River (Brazil)

Haplosternum littorale

83

[37]

Source: Silva-Cavalcanti J et al. Environ Pollut 2017, 221,218-226.

Note: The frequency indicates the percentage of individuals observed with the plastic debris inside the gut.

it was found that a lot of species ingest MPs. The data provided in Table 12.1 show the percentage of individuals observed with plastic debris inside the gut, shown as frequency percentage. Among the estuary species, the frequency percentage was highest in Catborops agassizzi collected from Goina estuary (Brazil) in the year 2011; it had ingested debris percentage of approximately 33%, which is quite high. Other species like Catborops spixi and Sciades berbergii showed the frequency equal to 18%. The genus Stellifer had ingested debris frequency percentage between 6% to 9%; specifically, Stellifer brasilliensis (found lowest among estuary species observed) and Stellifer stellifer had 6.9% and 9.2%, respectively, of ingested debris frequency. Other species like Eugeress brasilianus, Eucinostomos melanopterus, and Diapterus rbombeus were found with 16.3%, 9. 2% andll.4% of frequency debris, respectively.

The reports from the species thriving in Lake Victoria on the African continent showed an almost static frequency percentage of 20% among the studied species bates niloticus and Oreocbromis niloticus, studied quite recently in the year 2016 [31]. There was a high frequency of ingested debris among the species of river habitats; so far, Haplosternum littorale collected from the Pajeu River (Brazil) had a remarkably high (and the highest) frequency percentage of 83%. It is predicted to be hazardous for humans via the food chain; however, it is just a hypothesis as actual effects are yet to be analyzed. Other species collected from the Brazos River Basin (US) also showed high percentages of

Showing some of the studied species having a considerable frequency of ingested MPs

FIGURE 12.4 Showing some of the studied species having a considerable frequency of ingested MPs (e.g., Gobio gobio, Sciades herzbergii, Catborops spixii, Diapterus rhombeus, Stellifer stellifer, Catborops agassizzii and bates niloticus).

ingested debris frequencies: Leponis megalotis and Lepomis macrocbirus were observed with 44% and 45% frequencies, respectively [25]. Sanchez examined Gobio gobio from seven rivers of France in the year 2014 and found a range of frequency percentage of 9.5%-4.2% [35]. The overall result shows that the species thriving in the rivers are mostly affected by the MPs contamination. The reason behind this could be because the river is vulnerable to various sewage discharges along with factory wastes, so the chance of contamination is highest.

According to the hypothesis, the biomagnification of MPs is likely to be highest through river water species, and the consumption of the infected fish with MPs can be hazardous for humans also.

 
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